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Hydrogen embrittlement (HE) is one of the most devastating and unpredictable, yet least understood, mechanisms of failure experienced by engineering components. The presence of hydrogen leads to a severe degradation in mechanical properties and consequently a loss in structural integrity of a vast range of metals and alloys. Despite considerable research over decades, the precise mechanisms responsible for the embrittling process are still not understood. A key factor limiting our understanding is the difficulty in experimentally observing the distribution of hydrogen within a material, particularly at the atomic scale. Even ultra-high resolution electron microscopy cannot distinguish hydrogen atoms from the surrounding material in engineering materials. The Oxford Atom Probe group, working with colleagues at Sheffield, Zurich and Brisbane, report in Science the use of isotopic doping for the unambiguous 3D characterisation of individual hydrogen atoms within a ferritic steel. The research demonstrates the first direct atomic-scale observation of the precise manner in which a microstructural feature acts to trap hydrogen, in this case within the core of carbides. The techniques developed are not limited to steels, and may prove significant for other technologically relevant systems, such as nickel-based superalloys and titanium alloys where hydrogen can play an important role in degrading in-service performance.
Electron-phonon interactions from first principles
Rev. Mod. Phys. 89, 015003 (2017)
Environmentally-assisted grain boundary attack as a mechanism of embrittlement in a nickel-based superalloy
Acta Materialia 126 (2017) 361-371
Electrically tunable organic–inorganic hybrid polaritons with monolayer WS2
Nature Communications 8, 14097 (2017).